Smoothing the 12v supply to my Navtex

[DavidJ]

I've noticed that everyone elses NAVTEX works better than mine. When I look at the signal profile, it is greatly improved if I switch the shore power off. Is there a maplin type gadget which will smooth the 12v shore power supply
David

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[Talbot]

There is an Icom one used for SSB installation on commercial vessels. IIRC it is a PS65 This will provide a smooth 12v even up to 30amp discharge.

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[Wiggo]

Yes. Maplin part #VW45 - £4.99. Sorted all my TV interefence out, copes with up to 20A...

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[paulrossall]

The Maplin part VW45 is a Noise Suppresor which it says "removes alternator noise".
I am not technical but I was interested in a gadget that provides a constant voltage supply and I don't think this is it. It may well cure the problem the origional poster had...I don't know. Paul

<hr width=100% size=1>" there is nothing-absolutely nothing-half so much worth doing as simply messing about in boats".

 

[MainlySteam]

I assume that the noise is generated on board by your charger, invertor or such, rather than coming into the boat on the ac lines and just being radiated on board.

If the noise is generated on board it can be a difficult problem to beat. I have had alot of success using the noise suppressors available to be used in 12v supply to stereos in cars - we do not have Maplins here for me to physically check but the VW45 referred to others looks on the internet like the exact same thing (the ones I mean have three terminals and are normally a mixture of inductors and capacitors inside sized to carry the required current eg 5A, 10A, 20 A or whatever). While the Maplins site refers to alternator noise, they do in fact work on other noise as well. Due to the different possible transmission modes of the noise on the 12v cabling they are not always successful but are usually my first line of attack - I actually carry a spare on on my own boat.

If that does not work, then the Navtex being a receive only device allows experimentation in breaking of hum loops etc (should they be the problem) in the antenna system by use of capacitive breaks in the antenna transmission line to defeat them, but unless you have relevant experience I suggest that be left to an experienced professional. Hum loops are especially likely when using an active antenna and while I have not tried this, one of the above noise suppressors in the active antennas power supply may assist (that is if it is not powered directly from the Navtex itself).

It may, but usually not, help if the Navtex antenna cable is rerouted away from any nearby parallel dc/ac cabling.

If the noise is coming in on the ac lines themselves from the marina supply and then being radiated within the boat then I believe that its solution is probably beyond normal amateur resolution.

Good luck

John

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[Nauti Fox]

Interesting,got exactly the same problem,its definately boat rather than shore power as it does it at any marina(mind you we have got 30year old wiring)I'll try the Maplin soloution.
Al.

<hr width=100% size=1>No dear,the water goes in the other one.

 

[DavidJ]

Thanks Chaps

Thanks for the replies
For £4.99 the Maplin solution is worth a try. John's thought that the interference could be picked up by the ariel (not along the 12v line) is one I hadn't thought of and I will try moving the ariel to see if the effect changes.
I suspect though that the transformer is giving out a too rougher voltage for NAVTEX although all my other devices work very well and the boat is only a couple of years old.
regards
David

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[Wiggo]

Yes, it's sold to suppress alternator noise. It's just an LC filter, with a big transformer as the choke, but it does an excellent job of damping the noise on the 12V line that the DVD player was generating (I presume it was motor noise). At a fiver, it has to be worth a go for openers...

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